Sealed potentiometer



Nov. 23, 1948. GORDY 2,454,278

SEALED POTENTIOMETER Filed July 29, 1946 Patented Nov. 23, '194,8

UNI T ED` STAT ES F IrC-E1l 2,454,278 L SEALED Po'rEN'rloMarmi.l

IrvingGordy, Eatontown;fN."J.\` l' ApplicationJuly 29, 1946,-Serial No. 686,829

(Cl. 20k-55);-

(Granted under the act f.=.March .3, 1883, as;-

a-mended April 30, 1928;-v370-\O.G..757f) 7 Claims.

The invention described herein may be manufacturedfand used by or Afor the Government for governmental purposes without payment to me of any royalty thereon.

This invention relatesv to limprovements `in p0 tentiometers, rheostats, andisimilar electrical resistance devices.

An essential obj ect of ythis invention is to provide a potentiometer, rheostat, and the like, which is arrangedand constructed so `that all the electrical portions -of the component lare protected from deleterious substancesrpresent in the atmosphere, such asrnoisture,` salt, dust,'etc.

Another object of this invention is .to providea device `of this character which has its electrical resistance means protected by sealingit hermetically in theresistorcasing.-A

Amore. particular Aobject of this invention is to protect and seal the resistance stri-p inthe casing by-the use of a thin metal diaphragmf-or disc mounted between said strip and an open end on the casing, saidy diaphragmbein-g provided with bellows so `as to allowvfor iiexing of the diaphragm into engagement with the select-ed portion of the resistance strip. i

These :and .various other` objects and advantages are attained with this invention, as will be'- comeapparent` from the followingdeseription, taken -in :connection i withv the accompanying drawings wherein .the invention is shownin'its preferred form, it being evident that otherwarrangements vand forms of construction maybe resorted to in carrying out the objects and purposes lowerendl I and has an opening I21at the upper Y encLrtheicasing being constructedof ceramic or otherfinsulatingmaterial. Flange means I3 extends radially outward from the open end of the casing and is provided with apertures I4 forre-f ceivingscrews I5 whereby the mechanism may be.;y mounted for operation Aonto a panel .I 6 or the likev The screws I5 are shown as havingtheir head ends =held'in amet-al retaining .ring I'I which. is

therewithiweldediontoi'thejpanelnI 6; so asftoi exel vtendiiromithe-*r-ing. :through .a washer'.- |85v and.. throughi:saidflangermeans I3. Thezcasingmay f also be soldered directly-.to the panel, wlierezease.r of-replacement of the lcontrol is Anot important.

Thesresistan'cexst-rip- 2 I'is 'shown hereinfsas fine cludingathe .wire Lcoil; 2 2 :wound @upon'a suitable ine: sulatingamemberi23. The said l:member is mount# edfinth'e ycasing and mayzextendifromthe closed.:

end-.I I =of the casingfitowardpthe openingtasshown hereinj.or;it .maybe mounted vso-.as toiextenda'tzav slantain the teasing. substantially parallel .to the:

sealing'meanszprovided. zthe'reover.

A 'diaphragmor'disc 24.101? metal, such. as Phosf. phor bronze;iberilliuingcopper, etc., .is mountedin i the casing between the opening I2 andthe vresistance ,strip 2l, and'it is normally spaced from said str-ip.. asiindicated at the right-hand iside in'Fig. 1. This diaphragm is preferably 'conical in shape'andw` it has .its conicalend25 extending into thevcasing and.'mountedwithsealingfsoldermeans 26 on a; tubular member4 or` part '2l extending. inwardly from `the end-II ofzthe insulating casing, asindicated in the drawing. The diaphragm is mountv ed. to allow ilexing .or yielding movement in the casingrand it is therefore .provided with an annular bellows 428 around its outer or peripheral edge' portion, .said bellows being :preferably integral with the diaphragm and'being sealed .to the casy ingaroundl the Vopen end IZ-with a solder seal 29.` The resistance strip is thus hermetically sealed in the. casing beneath said diaphragm y24 with its bellows 28.

An operating member is shown herein as in-l which extends rotatably` cludingv a shaftV 3I through a collar` 32 mounted in panel I 6. From a head .33 at the inner end of the shaft extends an arm 34 provided at its free end with a shoe 351 which engages and is movable over the conical conductive diaphragrn24,v in such a manner as to depress and'flex the engaged part of the diaphragm into contact with the selected porti-on of the resistance strip 24 to include ythe desiredl amountl of resistance, as indicated at the lefthand 'side of Fig. yl. A spring 3 'I between collar 32 and head 33 urges'arm 34 with shoe 35 down to flex diaphragm 24 onto -strip 2 I.

A terminal post 38 extends through the end II of the insulating casing, `beineT `solder-sealed there- .in, and it has a wire39 connecting its inn-erend electric-ally with thediaphragm 24, while an elec- .tricity conductor 40 'is connectableto its outer end.

In the..potentiometer, a pair of terminal posts 4I -l and 4I are 4likewise extended through the casing fand solder-.sealed therein, `said posts having their inner ends connected by wires 42 and `42 with the opposite ends of the resistance strip 2 E, while their outer ends are connecta-ble to electricity conductors 43 and 43', in the usual manner. For the rheostat, one terminal post lll is used.

I claimt 1. In a dev-ice of the class described, a casing having a casing wall and closed except for an opening at one end, electrical resistance means mounted within the casing, a metal sheet electrical contact member extending completely across the casing b-etween said opening and said resistance means in juxtaposed spaced relation to the resistance means .and having a flexible supporting and sealing portion adjacent the casing wall to secure it flexibly within the casing in spaced juxtaposed relation to the resistance means and protect and hermetically seal the resistance means within the casing between said metal sheet contact member and the closed end of the casing, terminal vposts sealed in the casing wall between the ilexible metal sheet contact member and the closed end of the casing and being each electrically Iconnected at the inner end, one to the resistance means and another =to the flexible metal sheet contact member, movable operating means supported in the open end of the casing, outwardly of said flexible metal sheet contact member, and oper-able upon said metal sheet contact member to force the portion thereof contacted by said operating means into contact with a selected Dortion of said resistance means, and thereby establish an electrical circuit between said terminal posts through the `contact relation between the flexible metal sheet contact member and the resistance means.

2. In a device of the class described, an insulating casing having an inner wall and an opening at one end only, electrical resistance means mounted -in the casing, a sheet metal flexible diaphragm mounted in the casing across the open end in juxtaposed spaced relation to the resistance means and positioned outwardly of said resistance means to seal the resistance means within the casing, said diaphragm having bellows means provided Vat its outer edge portion adjacent the inner wall of the casing and secured to the inner wall of the casing to prot-ect and seal .the resistance means hermetically therein, a plurality of electrical terminal posts extending through the casing wall in sealed relation thereto, an electrical connection between the inner end of one of said posts and said resistance means and another electrical connection between another of said posts and said diaphragm, and movable operating means supported outwardly of said diaphragm and extending into the casing, having a member thereon to contact with said diaphragm to ex said bellows and displace said sealing diaphragm into electr-ical contacting relation with a selected part of said resistance means to complete an electrical circuit lbetween said terminal posts through the resistance means and said sealing diaphragm.

3. In a potentiometer and the like, an insulating casing having an opening in one end, means whereby to mount said casing, an electrical resistance strip mounted within the casing, a conical contact diaphragm of electrically conductive material extending across said opening within the casing with its apex extending toward the closed end. of the casing, exible supporting and sealing means formed at the peripheral edged portion of `the diaphragm in supporting and sealing relation to the inner wall of the casing wherebi7 the diaphragm is yieldably secured to the casing across said opening and in spaced juxtaposed relation to the resistance strip to seal the resistance strip hermetcally within the casing, three electrical terminal pos-ts extending through the casing wall in sealed relation thereto between the diaphragm and the closed end, one of said posts having its inner end electrically connected to said diaphragm `and the other two posts each having its inner end electrically connected to one of the 0D- posite ends of the resistance strip, and a movable operating member extending into the opening in :the casing having diaphragm displacing pressure means thereon slidable on the outer portion of said diaphragm whereby to move said outer portion thereof into electrical contact with a selected part of said resistance strip.

4. In ia device of the class described, a cupshaped insulating casing having an opening at one end and means at said end whereby to mount the casing on a support, a resistance strip flxedly mounted within the casing, a conical metal electrically contacting and sealing diaphragm disposed across said opening in spaced juxtaposed relation to the strip and supported at its apex within the casing, a bellows formed 4on 'the peripheral edge portion of 'the diaphragm and supported at its peripheral edge on the inner wall of the casing in sealing relation to said inner wall and said diaphragm whereby the latter is yieldably secured to the casing around the inner periphery of said opening to seal the resistance strip hermetically within the casing electrical terminal posts extending through the casing wall in sealed relation thereto between the closed end of the casing and the diaphragm and bellows closure, one of said posts having its inner end electrically connected to said diaphragm and another :post having its inner end electrically connected to the resistance strip, an operating shaft extending into said opening having an arm on its inner end, and pressure means carried by the arm between .the diaphragm and said opening and movable on the diaphragm to llex a portion thereof into electrical contact with a selected part of the resistance strip.

5. In a potentiometer and the like, a substantially tubular ceramic casing closed at one end and having an opening at the other end, a curved resistance strip mounted within the casing, a conical metal electrical contact diaphragm member extending across the casing between the resistance strip and the opening, means supporting the conical diaphragm at its apex within the casing in spaced juxtaposed relation to the resistance strip, sealing and securing bellows means on the peripheral edge portion of said diaphragm and secured in sealing relation to the inner wall of the casing to yieldably secure the same to the casing and completely close said opening to protect and hermetically .seal the resistance strip lwithin the casing, a plurality of electrical terminal posts extending through the casing wall and sealed therein between the closed end of the casing and the conical diaphragm, yan electrical connection between the inner end of one of said terminal posts and said diaphragm and an electrical connection between the other electrical terminal yposts and the opposite ends of the resistance strip, and movable operating means between the opening and the diaphragm, engaging the diaphragm at a point near its periphery to force the latter into electrical contact with a selected part of the resistance strip, for including a selected desired resistance of the resistance strip in the circuit between said terminal posts.

6. In a hermetically sealed variable resistance device of :the class described, an impervious cylindrical casing closed at one end and opened at its other end, a flexible resilient impervious electrical contact diaphragm member extending across the interior of the casing intermediate the closed end and its other end to form a hermetically sealed chamber within the casing between the diaphragm member and the closed end of the casing, a cyclindrically curved resistance strip member concentrically arranged and fixed within the casing within the cylindrical chamber thereof having an electrical resistance contact surface xed in closely spaced juxtaposed relation to the adjacent surface of said electrical Contact `diaphragm member, an electrical terminal post extending through the casing from the exterior to the interior of Athe hermetically sealed chamber electrically connected at one end to the resistance strip, a second terminal post fixed on said casing and electrically connected to said electrical diaphragm member, a rotary operating shaft concentrically journaled for rotative adjustment within the opened end of the casing, a resilient pressure means xed on the shaft having a radially offset pressure shoe tensioned -against the outer portion of the vdiaphragm and towards said resistance strip for flexing the outer radial portion of the diaphragm toward the sealed chamber and into electrical contact with the adjacent portion of said resistance strip to establish an electrical resistance circuit Within the hermetcally sealed chamber and between said terminal posts through the resistance strip and said electrical contact diaphragm.

7. Apparatus as claimed in claim 6 including flexible bellows means formed at the periphery of said diaphragm adjacent the interior wall of the casing to provide increased flexibility between the outer portion of the diaphragm and its sealed and connected portion with `the inner porti-0n of the casing.

IRVING GORDY.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,776,177 Bruno Sept. 16, 1930 1,851,933 Schellenger Mar, 29, 1932 2,000,178 Kenney May 7, 1935 

